Process of refining metals.



KARL OTTO KRETSOHMER, OF ELIZABETIL NEW JERSEY, ASSIGNOR OF TWO-THIRDSTO UNITED STATES PATENT OFFICE.

CHARLES J. QANDA AND FERDINAND E. OANDA, OF NEW YORK, N. Y.

PROCESS OF REFINING METALS.

Application filed October 18, 1907.

To all whom it may concern:

Be it known-that I, KARL OTTo KRETSOH- MER, citizen of the UnitedStates, residing at Elizabeth, New Jersey, have invented certain new anduseful Improvements in Processes of Refining Metals; and I do herebydeclare the following to be a full, clear, and exknown to me. itselfrapidly through the molten steel and 1s act description of theinvention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to an improved process of refining metals and inparticular to the refining of steel during the process of manufacturingthe same. v

The object of my invention is to provide a composition or flux whichwill free the molten steel from oxids and also from particles of slaIgsuspended in it.

t is well known that one great difficulty hitherto encountered in themanufacture of steel has been to remove the oxids and slag so as to forma homogeneous product. The molten steel running from the furnace to theladle carries impurities intimately commingled with it and the amount'ofsuch impurities is increased by contact of the metal with the air. Ithas been common to add various ingredients to the molten metal to serveas fluxes, for the purpose of causing the impurities to rise to the topof the molten metal, whereby the metal in a refined condition can beseparated from the impurities which accumulate as slag. While theingredients heretofore employed as fluxes have been of advantage inrefining the steel, they are not entirely satisfactory in practice inattaining the desired result, probably owing to the fact that they donot disseminate with sufficient rapidity through the molten steel toallow them to come into contact and react with the impurities in theshort time permissible for the treatment.

I have discovered that if anhydrous or even partly dehydrated compoundsof boron and in particular anhydrous boron-trioxid, B 0 be used as aflux, they have marked advan tages in practice over anything hithertoSuch a flux will distribute exceedingly active in combining with themetallic oxids in the molten steel to form chemical compoundsconstituting a thin fluid flux which rises rapidly to the top of themolten metal and there accumulates as a layer impenetrable to the air,thus serving to protect Specification of Letters Patent.

' tion.

sults.

Patented Sept. 8, 1908.

Serial No. 398,005.

the liquid metal below. Furthermore, the rapidly rising thin fluid fluxincloses and carries along the particles of sla which may bedisseminated through the mo ten metal, thus quickly refining the metaland leaving it in an excellent homogeneous condition.

In order to obtain the desired anhydrous or partly dehydrated compoundsof boron and their combination with other chemical compounds, I maysubject boric acid' or borates of any kind to high temperatures in orderto drive off the water of crystallization and also the water of itschemical constitu- For example, upon subjecting boric acid to atemperature of about 160 0., the same is partly and at fusion say 600 C.completely dehydrated according to the length of the treatment. Theresultant product, either completely or partly dehydrated boric acid isparticularly adapted for my purpose. The completely dehydrated productis known as boron-trioxid, B 0 and gives the best results, although thepartly dehydrated boric acid is capable of satisfactory action for thepurpose intended.

By submitting borates of any kind, for example, biborate of soda,(Na,B,O,+ 1OH O) to a high temperature, for example, about 150 C., theanhydrous borate may be obtained and these act well in carrying out myprocess. Furthermore, a mixture of these various dehydrated compounds ofboron may be used, if desired, with ood re- While the proportion of sucdehydrated compounds of boron which are added to the molten metal mayvary according to the composition and amount of impurities in the moltenmetal, I have found that the addition of the boron trioxid in theproportion of 2 pounds to each ton of molten steel or thereabout, givessatisfactory results. When the anhydrous borates are employed theyshould be added in the proportions of about 4 pounds to each ton ofmolten steel.

In carrying out my process, I add the flux or fluxes hereinbeforespecified to the ladle while the same is being charged from the furnace,or I may add the said flux or fluxes to the metal while it is flowingthrough the trough from the furnace to the ladle.

I am aware that it may be difficult and therefore perhaps commerciallyimpracticable-to obtain the compounds of boron in an absolutelydehydrated or anhydrous condition, but a sufficiently close approach tothis desirable condition is readily obtained in practice, and,therefore, it is to be understood that by the use of the terms anhydrousor dehydrated in the claims, I mean substantially anhydrous andsubstantially deh drated, thus including those conditions wfiere thecompound em loyed is only partly dehydrated or part y anhydrous, yetsufliciently free from water to accomplish the desired advantageousresults. By the treatment of the desired compounds to remove the waterof constitution and crystallization or the' direction, and leave theremaining metal in a porous condition. These serious disadvantages areentirely avoided by my invention. Having thus fully described myinvention, what I claim is:

1. The process of refining metals, which consists in subjecting themetal While in a molten condition to the action of previously dehydratedcompounds of boron.

2. The process of refining metals, which consists in adding a previouslydehydrated compound of boron to the molten metal after said metal hasleft the furnace.

3. The process of refining metals, which consists in adding an anhydrouscompound of boron to the molten metal while charging said metal into theladle.

4. The process of refining metals, which consists in subjectin themetal. while in a molten condition to t e action of previously Idehydrated compounds of boric acid.

5. The process of refining metals, which consists in adding a dehydratedborate to the molten metal while charging said metal into the ladle.

6. The process of refining metals, which consists in adding a dehydratedborate to the molten metal after said metal has left the furnace.

In testimony whereof I hereunto aflix my signature in the presence oftwo witnesses.

KARL OTTO KRETSCHMER.

Witnesses:

RUssELL MILES, T. J JoNEs.

